 Good day everybody. This is Dr. Sanjay Sanyal, Professor, Department Chair. I'm going to give you a demonstration of the full articulated vertical column. So what I'm holding in front of me, this is the articulated vertical column. And you can see this is the base of the skull here. This is the occipital bone. And we can see that it's articulating with atlas up here and below that is the axis. Then you have the cervical vertebrae. And if you were to look behind, we can see that this is the cervical vertebrae here. This is the vertebra prominence. And then we have the thoracic vertebrae. And below that, we have the number vertebrae. And finally, we have the sacrum here. So this is the full vertebral column. The reason why I'm holding it up in the lateral view is to show you the vertebral column has got certain curvatures. These are being divided into what are known as the primary curvatures and secondary curvatures. The primary curvatures are those which mimic the fetal curvature when the fetus was inside the mother's womb. Therefore, the primary curvature is the thoracic. It's a normal thoracic kyphosis. And the second normal primary curvature is the sacrum. It is already curved forward. So these two maintain the fetal curvature. In contrast, we have two secondary curvatures. Number one is the cervical curvature, which is in the direction opposite to that of the fetal curvature. This is because at the third month of age, the child tries to raise the head up. And therefore, this cervical spine bends in the opposite direction. And the next one is the lumbar curvature, which also we can see is a normal lumbar lordosis. This is at the sixth month of age when the child tries to sit up. And therefore, the lumbar spine gets bent in the opposite direction. So these are the two primary and the two secondary curvatures. Now let's take a look at some abnormalities that we can see here. One of the abnormalities is abnormal thoracic kyphosis. The thoracic spine gets abnormally curved forward. And that is sometimes associated with something called hunchback, which I shall tell you just a little later. And that can reduce restrictive lung disease. This is a lateral x-ray to show extreme thoracic kyphosis caused by excessive osteoporosis of thoracic vertebrae. The other one is abnormal lumbar lordosis. The lumbar spine gets bent excessively backwards. You see this lumbar lordosis and the thoracic kyphosis. Normally, they are slightly curved. They are called normal. But when it becomes excessive, then it's called abnormal. The normal lordosis maintained by the muscle here, which is the soleus major. So therefore, this is the one which maintains the normal lumbar lordosis and indirectly maintains the thoracic kyphosis. On the other hand, the muscle in front of the abdomen that is rectus abdominis is considered as an anti-lordotic muscle. When the muscle balance between these are lost between the abdominal and wall muscles and the back muscles, then we tend lordosis. Another example of lordosis is when people wear very high heels, then automatically there is a tendency to fall forward. And so therefore, the back muscles tend to have to contract excessively and the curvature of the lumbar spine becomes excessive to compensate for the tendency to fall forward. And therefore, they develop lumbar lordosis. During pregnancy also, because of the excess weight in the front, the tendency for the person to lean back. And therefore, that is also called the lordosis of pregnancy. While we're on this topic, I would like to draw your attention to a few other points. Take a look at the lumbosacral joint here. This is the lumbosacral joint. The superior surface of the sacrum normally makes an angle with the horizontal, which is approximately about 30 degrees. But when there is an abnormal lumbar lordosis, then this angle, which is referred to as a sacral horizontal angle or SHA, it becomes more than 50 degrees because of the excessive lordosis, the horizontal surface and the surface of the sacrum, they make an angle more than 50 degrees. Therefore, SHA becomes high in lumbar lordosis. Apart from that, we can get something called lateral curvature. That tends to generally occur in the thoracic spine. That is called scoliosis. This is a very complicated abnormality. This is not just associated with lateral curvature, but it can be associated with the rotation of the thoracic vertebra itself. And the thoracic vertebra, as we know, give attachment to ribs. When the thoracic spine gets curved on the convex side, the posterior ribs on the convex side of the curvature, suppose the thoracic spine is curved like this. On the convex side, the posterior ribs jut backwards posteriorly. And the concave side, the anterior ribs jut anteriorly. Therefore, when you ask the patient to touch bent down and touch his or her toes, because of the posterior ribs jutting backwards posteriorly on the convex side, they produce an elevation on the back of the chest. And that is called a rib hump. So that can sometimes not be seen when the person is standing straight. But when the person bends down, then it becomes obvious that is the rib hump. This is an x-ray of the thoracolumbar spine to show thoracolumbar scoliosis. This is an x-ray of the thoracolumbar scoliosis before surgery and the result after surgery. Note the increase in height. This thoracic kyphosis may be associated with scoliosis. Then it's called kyphoscoleosis. And then it can produce what is known as restrictive lung disease. One of the conditions and not some of this is a condition known as Friedrich etaxia. That is associated with kyphoscoleosis. And the final point which I want to mention was that in the thoracic region, as we know, there is very little or no movement. There is only a very small nominal movement and that is a rotatory movement through an imaginary axis going through the middle of the vertebral bodies. A small movement is achieved by a small group of muscles of the transversal spinal cord in the back. And one of that muscle is referred as a rotator's muscle. It starts from the transverse process of one vertebra and gets attached to the spinal process of the vertebra above. These slips of muscle called the rotators, they are the ones which are more prominent in the thoracic region and they are responsible for the slight rotatory movement, a very slight rotatory movement in the thoracic vertebra. These are some of the points which I wanted to mention to you about the vertebral collar as a whole and the curvatures and a few other associated points. Thank you very much for watching. Dr. Sanjay Sanyal signing out. If you have any questions or comments, please put them in the comment section below. Have a nice day.